MBE chamber for group-III nitrides (reactive and plasma-assisted)

This system is devoted to the growth of group-III nitride heterostructures using NH₃ and/or a nitrogen plasma on 3" substrates, and has been custom-built by CreaTec. The growth chamber has a novel evacuation concept which is designed to maximize the throughput for growth with NH₃. Two turbo-molecular pumps are used for evacuating the growth chamber, each connected upstream of a liquid-nitrogen cooled baffle. The shrouds of the growth chamber and the effusion cells are cooled with ethanol to prevent condensation of NH₃. This scheme allows continuous operation of the system while retaining a base pressure in the low 10^-10 mbar range.

At present, the system is equipped with solid-source effusion cells for Ga, Al (the latter with an active cold lip), In, Mg, and Si. Active nitrogen is provided either by a custom-designed NH₃ injector or by either of two ethanol-cooled RF N₂ plasma sources (Specs and SVT). For obtaining a high throughput, up to ten 3" wafers can be loaded and outgassed simultaneously in the cryo-pumped loadlock chamber. An additional chamber equipped with a DC magnetron is connected to the MBE system, allowing metal-deposition on the backside of transparent substrates. Transfer of the wafers to the sputtering and the growth chamber is automated. Growth is controlled by a custom-designed MBE software, and monitored by RHEED and pyrometry.